There is overwhelming scientific evidence that (n-3) highly unsaturated fatty acids such as docosahexaenoic acid (DHA) have a positive effect on cardio-circulatory diseases, chronic inflammations and brain disorders. The (n-6) fatty acids such as eicosapentaenoic acid (EPA) on the other hand have been noted as intermediate metabolites within the eicosanoid steroids, such as prostaglandins, leucotrienes or the like.
Currently, the main source of these highly unsaturated fatty acids is fish, with EPA and DHA noted within various blue fish (such as sardines and tuna) at amounts around 20% and 10%, respectively. It is believed that such a fatty acid profile occurs through the natural selection of optimal ratios for optimal performance within each species of fish. Yet, if one intends to use fish oil as the sole source of these lipids, several disadvantages exist, such as problems with flavor taint, uncontrollable fluctuations in availability and natural fish oil content variability. In addition, if one intends to obtain a highly purified (n-3) or (n-6) oil from these sources, it is very difficult to preferentially separate and purify.
Previously disclosed is a Thraustochytriales eukaryote, ONC-T18 and related organisms, capable of producing high amounts of DHA and EPA as well as other preferred fatty acids. ONC-T18 is disclosed in International Application PCT/IB2006/003977 and U.S. provisional applications 60/751,401 and 60/821,084 which are all herein incorporated by reference for information at least related to ONC-T18 and fatty acids produced therein. The manipulation of the DHA and EPA pathways is desirable. Disclosed herein is the isolation and characterization of two enzymes from ONC-T18 involved in these pathways, a D4 desaturase and a D5 elongase.